I've been slowly working my way through Guns, Germs, and Steel for a while now. It's an interesting read overall, but this one section really got me thinking.

What were the factors that tipped the competetive advantage away from [hunting-gathering] and towards [farming]? ...five main contributing factors can still be identified; the controversies revolve mainly around their relative importance.

One factor is the decline in the availability of wild foods. The lifestyle of hunter-gatherers has become increasingly less rewarding over the past 13,000 years, as resources on which they depended have become less abundant of even disappeared... most large mammal species became extinct in North and South America at the end of the Pleistocene, and some became extinct in Eurasia and Africa, either because of climate changes or because of the rise on skill and numbers of human hunters.

I've never heard this part of the argument before: that humans may have turned to farming because of the lack of large, huntable animals after the last ice age. It's fascinating to consider that the recent set of the Earth's cycles of natural climate change have not only been more favorable for humans to develop farming and complex civilization, but that they may have also forced our hands in the first place.1

1. And that man-made climate change could be the end of that same civilization.